Optical sensor with integrated pinhole

Patent metadata

Field	Value
Publication number	US-10069023-B2
Application number	US-201414157891-A
Country	US
Kind code	B2
Filing date	Jan 17, 2014
Priority date	Jan 18, 2013
Publication date	Sep 4, 2018
Grant date	Sep 4, 2018

Abstract

An optical sensor includes a semiconductor substrate having a first conductive type. The optical sensor further includes a photodiode disposed on the semiconductor substrate and a metal layer. The photodiode includes a first semiconductor layer having the first conductive type and a second semiconductor layer, formed on the first semiconductor layer, including a plurality of cathodes having a second conductive type. The first semiconductor layer is configured to collect photocurrent upon reception of incident light. The cathodes are configured to be electrically connected to the first semiconductor layer and the second semiconductor layer is configured to, based on the collected photocurrent, to track the incident light. The metal layer further includes a pinhole configured to collimate the incident light, and the plurality of cathodes form a rotational symmetry of order n with respect to an axis of the pinhole

First claim

What is claimed is:

1. An optical sensor, comprising:
a semiconductor substrate having a first conductive type;
a photodiode formed on the semiconductor substrate, the photodiode comprising:
an epitaxial semiconductor layer having the first conductive type, wherein the epitaxial semiconductor layer is configured to generate current responsive to reception of incident light; and
a plurality of cathodes having a second conductivity type opposite from the first conductive type and being formed on the epitaxial semiconductor layer, the cathodes of the second conductivity type extending to a surface of the epitaxial semiconductor layer, the cathodes configured to make electrical connections to the epitaxial semiconductor layer and, based on the generated current, to track the incident light, the optical sensor further comprising:

a metal layer formed over the photodiode opposite the semiconductor substrate and comprising a pinhole configured to collimate the incident light,
wherein the plurality of cathodes form a rotational symmetry of order n with respect to an axis of the pinhole, where n is an integer greater than or equal to two;
wherein the collimated incident light only impinges an anode of the photodiode.

2. The optical sensor of claim 1 , wherein the metal layer is fabricated using an integrated complementary metal oxide semiconductor (CMOS) process.

3. The optical sensor of claim 1 , wherein the first conductive type is p-type and the second conductive type is n-type.

4. The optical sensor of claim 1 , wherein a distance between each of the plurality of cathodes and the pinhole is not greater than an electron diffusion length.

5. The optical sensor of claim 1 , wherein the optical sensor comprises an array of a pinhole integrated sensor, wherein each of the pinhole integrated sensor comprises a plurality of cathodes and a pinhole integrated with the pinhole integrated sensor.

6. The optical sensor of claim 1 , wherein the pinhole has a shape of one of a stripe, a plus sign, a circle, a triangle, a rectangle.

7. The optical sensor of claim 1 , wherein the plurality of cathodes form an array of dots, triangles, stripes, rectangles.

8. The optical sensor of claim 1 , wherein the generated current is based on an angle formed by the incident light and the semiconductor substrate.

9. An optical sensor, comprising:
a semiconductor substrate having a first conductive type;
a photodiode disposed on the semiconductor substrate, comprising:
a first semiconductor layer having the first conductive type, wherein the first semiconductor layer is configured to collect photocurrent upon reception of incident light; and
a second semiconductor layer comprising a plurality of cathodes having a second conductive type and formed on the first semiconductor layer, the cathodes of the second conductivity type extending to a surface of the second semiconductor layer, the cathodes configured to be electrically connected to the first semiconductor layer and, based on the collected photocurrent, to track the incident light, the optical sensor further comprising:

a metal layer formed on the second semiconductor layer and comprising a shadow mask configured to collimate the incident light,
wherein the plurality of cathodes are n-fold rotationally symmetric based on an axis of the shadow mask, where n is an integer greater than or equal to two;
wherein the collimated incident light only impinges an anode of the photodiode.

10. The optical sensor of claim 9 , wherein the metal layer is fabricated using a complementary metal oxide semiconductor (CMOS) compatible process.

11. The optical sensor of claim 9 , wherein the first conductive type is p-type and the second conductive type is n-type.

12. The optical sensor of claim 9 , wherein the incident light is received by the first semiconductor layer after passing through the shadow mask.

13. The optical sensor of claim 9 , wherein the optical sensor comprises an array of a shadow mask integrated sensor, wherein each of the shadow mask integrated sensor comprises a plurality of cathodes and a shadow mask integrated with the shadow mask integrated sensor.

14. The optical sensor of claim 9 , wherein the shadow mask has a shape of a stripe, a plus sign, a circle, a triangle, a rectangle.

15. The optical sensor of claim 9 , wherein the shadow mask is suspended over the second semiconductor layer and is connected via the metal layer.

16. The optical sensor of claim 9 , wherein the plurality of cathodes are an array of one-dimensional configurations, two-dimensional configurations, or three-dimensional configurations.

Assignees

• Texas Instruments Inc

Inventors

• Becker James
• Edwards Henry Litzmann

Classifications

• H01L31/02327 Primary

  Electricity · mapped topic

• H01L31/103

  Electricity · mapped topic

• H01L31/02024

  Electricity · mapped topic

• H10F77/957

  for position-sensitive photodetectors, e.g. lateral-effect photodiodes or quadrant photodiodes · CPC title

• H10F30/221

  the potential barrier being a PN homojunction · CPC title